Unconscious Resonance
The vibration spread up through the soles of my feet, and beyond the window the scenery lay drowned in the soft haze of evening.
The train car was packed with people heading home from work. As luck would have it, the only seats still open were two side by side.
We sat down together without a word. It wasn’t intentional, but the seats were narrow, so our shoulders pressed close enough to brush.
Yuzuki leaned back into the corner, and I settled beside her.
Neither of us spoke. We both stared down at our phone screens, using them as an excuse not to look up.
Just as that silence was beginning to drag, Yuzuki suddenly spoke.
“Who was that girl you were with this afternoon?”
The question dropped abruptly between the train’s rattles, without the slightest warning.
I lifted my head on reflex.
At that moment Yuzuki still hadn’t taken her eyes off her screen. Her gaze remained fixed somewhere on her phone while her voice drifted toward me.
“...What?”
“The one with the silver hair, long and straight, tied back in a ponytail. Her eyes were a reddish color too.”
“How do you even know that?”
I hadn’t told her anything about my afternoon yet.
When I turned to her with obvious confusion, Yuzuki switched her phone off.
Her fingertips slid slowly from the touchpad as she turned her head to face me.
“I just heard about it from Haruka.”
“...From Haruka?”
“Yeah.”
Maybe it was because the student body at Dracore Academy was so small. If news from this afternoon had already spread this fast, everyone must have been on pretty good terms.
“Are you and Haruka close?”
“...Well, it’s not bad. She has an unreasonably good personality. At least we could never end up on bad terms, right?”
That was true enough.
With Haruka’s personality, she would make friends anywhere she went.
“So who is she, really?”
I glanced out the window before answering in a calm tone.
“Her name is Luna. She’s someone Father brought with him.”
At that, Yuzuki’s eyebrows drew together sharply.
“...Father? Why would he suddenly—”
“I’m not sure. It seems she was helping with research at the lab. Then she transferred into the academy this time, and Father apparently handled the paperwork.”
“...Helping with research at the lab? What kind of research?”
“That part I don’t know either.”
Half the truth, half an evasion.
I hadn’t imagined Luna would be connected to Father’s side, but I could guess the general nature of the research. Still, admitting I knew anything about it would have been difficult.
Yuzuki paused for a moment, then asked quietly.
“But… why is that girl interested in you, Oppa?”
I shrugged.
“Who knows. Maybe she just found it strange that I’m a guy.”
“...Is that so? Well, I suppose that makes sense.”
A short sigh slipped from her nose. Yuzuki turned her gaze silently back to the window.
In the quiet that followed, several minutes passed before she spoke again.
“...If you’d been in the morning theory class, you’d already know, but—”
Having brought it up, Yuzuki hesitated. Her eyes lingered somewhere beyond the glass before carefully returning to me.
“They said that once the synchronization rate passes eighty percent, it shares more than just senses. Emotions get shared too. Even thoughts start to show through faintly…”
A complicated resolve crossed her face.
Then came the question.
“...What were you thinking while we were coupling, Oppa?”
“...What was I thinking?”
I faltered.
I couldn’t understand why Yuzuki was asking this. Simple curiosity? Or was she trying to confirm something?
I looked down for a moment, thinking, then decided to answer honestly. There was no reason to hide it, and honestly no strong emotion from that moment came to mind anyway.
“...I thought it was interesting.”
Yuzuki’s lips twitched in a tiny frown, as if the answer displeased her. Just for a second.
“And?”
“...And?”
I couldn’t continue.
That really had been all of it. In that moment I had been completely focused on the coupling itself—on getting used to the way Yuzuki’s sensations overlapped with mine.
“Hmm…”
My attitude drew a short, low breath from her, heavy with disappointment.
When I stopped speaking, Yuzuki turned her head slightly and looked straight into my eyes. This time she didn’t avoid my gaze; she studied me as if making certain.
But there was no lie on my face.
A foolishly honest expression, every genuine feeling laid bare. The face of someone who truly didn’t know what more he was supposed to say.
Only then did Yuzuki seem to understand.
The emotions that had flowed across during coupling hadn’t been sent consciously.
They had all been unconscious reactions he hadn’t put into words, and in the linked state they had poured into her completely.
Realizing that, she murmured almost without moving her lips, as if speaking to herself.
“...So that was in the realm of the unconscious.”
“Huh? What?”
I tilted my head. Yuzuki shook hers and looked away.
“Nothing. Never mind.”
With that, she rested her chin on her hand again and stared out the window.
The train was crossing a bridge just then, and below us the river glimmered faintly.
The water was calm, the current slow, yet it felt as though it stretched on forever.
She gazed at the scene blankly and thought. She had finally worked up the courage to ask, yet her chest still felt heavy.
And somehow the situation seemed even more complicated now. Were emotions that couldn’t be conveyed through words really this frightening and ambiguous?
On the other hand, she suddenly realized something else.
If that was the case, what emotions had Yuto felt from her during coupling?
Just as she had unconsciously absorbed his feelings and thoughts, perhaps he had received emotions she herself hadn’t been aware of sending.
That was terrifying.
What if she, too, had been leaking strange feelings from her unconscious, just like him?
Yuzuki tightened the hand under her chin. The scenery outside remained dark and empty, but her heart felt far more unsettled.
Today had been full of far too many things.
It was my first day at the academy, so I had been tense, and before I knew it I had formed connections with an overwhelming number of people.
Maybe that was why.
When I got home, I ate dinner and immediately fell asleep. My body was drained, and without any room for thought I was pulled under the covers as if I had fainted.
“...What time is it?”
When I opened my eyes, the room was dark.
Faint moonlight slipped through the window gap, casting blurred shadows across the wall. I picked up my phone and checked; it was two in the morning.
An awkward hour.
I rubbed the back of my neck, threw off the blanket, and got up. My mouth felt sticky. Thirst scraped at the back of my throat, and I knew I wouldn’t be able to fall asleep again without drinking something.
I quietly opened the door and stepped into the living room. The lights were off, but the familiar layout let me reach the kitchen without fumbling.
I opened the refrigerator, took out a bottle of cold water, poured a glass, and drank it in heavy gulps. The chill sliding down my throat cleared my head a little.
I set the glass down with a small sigh and was about to head back to my room when—
—Ahhn…
“...”
I thought I had heard something.
More precisely, it was Yuzuki’s suppressed moan.
I froze mid-step.
...What was that?
Was I still dreaming?
In the silent stillness of early morning the sound had been faint as breath, yet perfectly clear.
And it carried a familiar discomfort.
The first time I had succeeded in coupling and stood in front of my sister’s room.
The stifled sounds leaking from beyond the closed door. The wet, trembling breaths. And… the voice that had called my name.
The sound I had just heard was far too similar.
The moment I realized it, something in my chest began to tighten slowly. Not with tension, but with a strange heat.
My heart started to race, thump, thump, losing its rhythm.
I moved carefully. Placing no weight on my toes, making no sound.
Yuzuki’s door was closed. Inside was only silence. Yet within that quiet, something writhing seemed to stab into my brain.
I hadn’t even pressed my ear to the door, yet I could feel a pulse echoing from within the room.
Not from inside my own body, but from somewhere in there.
I stood in front of the door, held my breath, and listened.
Soon the sound came again.
—Haa…
It slipped into my ear like a suppressed sigh, or a fractured breath.
But the resonance was unmistakably the same as that time in my memory.
—Haa… uht…
From beyond the door, low and broken sounds leaked out intermittently. As if she were trying to kill them, yet they had grown too large to contain.
My breath caught. My lips went dry. The sweat on my forehead turned cold. I shifted the weight I had been leaning backward and moved it forward.
Unconsciously closer to the door.
That was when it happened.
—…Yuto…
It was clear. In the dead silence of this early morning, a single name spoken in a tiny voice rang through my head like ripples on water.
—Hut… you bad… bastard…
Beyond the door, breath tangled with the words first. Emotions creaked and burst outward.
—Why… are you the only one… who’s fine… ahhn…
It sounded like suppressed, exploding anger, yet at the same time like a resentful sob. I couldn’t tell whether regret or rage lay buried beneath it.
—Yuto… you trash bastard… you perverted bastard… how could you do this to your own sister…
It was hard to believe even while hearing it. But it was unmistakably Yuzuki’s voice.
Low and hoarse, yet clearly calling my name and pouring out emotion-laden curses.
I stood nailed to the spot in front of the door.
And then—
—…Ahhn… Does it turn you on? Are you getting off on this… you perverted bastard…
The moment those words reached me, my heart skipped two or three beats. Something beneath my skin tingled, and a weight dropped heavily inside my chest.
I kept my mouth shut, unable to breathe, and simply stood there.
With only a single door between us, those painfully vivid breaths.
The emotions Yuzuki was feeling, the warped pleasure, washed over me in waves.
—This is all because of you… why… are you making only me like this…
She was talking to the ‘me’ inside her imagination right now. In the darkness of her room, like a quiet nightmare.
—Honestly… during coupling you were only thinking about me, weren’t you? Tell the truth…
The question seemed aimed at me, yet it also sounded as if she were asking herself.
—I… know… I know how you see me inside, Oppa… I felt all of it during coupling… so why… do you keep saying no…
Heat transmitted even without skin contact. Even through one door, the vibrations of the emotions piled up inside rose along my fingertips.
—Haak…! Augh…! No… ugh… why won’t it… disappear…
Entangled breaths, sighs soaked in sweat and fever.
—Uht… Oppa… I really hate you… I hate it, but… the more I think about you the hotter my body gets… why…
And at the very end—
—Haaaa…
With Yuzuki’s final sigh, pushed out as if expelling everything, I heard the sound of her body collapsing onto the bed.
“......”
It was her body that had collapsed onto the mattress, but at the same time something inside me sank as well.
My head burned. Cold sweat beaded on my forehead, and a strange heat slid down the back of my neck. My heart had been pounding wildly for some time, and my legs felt helplessly locked in place.
Everything I had just heard—the words, the sounds—didn’t simply echo in my ears. They felt engraved somewhere deep inside me.
Even while she spat out I hate you, you’re a bad bastard, you pervert, every whisper, every breath, struck directly at some vital point within me.
Honestly, it felt like eavesdropping on a scene that belonged in porn. The only problem was that the characters in that scene were me and my own younger sister.
So even hearing her mix curses in with the words didn’t make me feel bad. If anything, it excited me.
The image of Yuzuki touching herself refused to leave my mind. I thought I would go insane.
I pressed a hand to my forehead, then grabbed a fistful of my hair. The heat would not subside.
And at the same time, the events of the day began to click into place one after another.
Why Yuzuki had acted so strangely after our coupling.
Why she had avoided me and tried to push me away.
—It had to be because she had glimpsed somewhere inside my unconscious through the coupling.
Those afterimages of emotions I hadn’t even been aware of myself.
...That was simply too unfair.
Was it wrong to feel desire when looking at a beautiful woman? That was human instinct, a perfectly natural reaction for any man.
Besides, that night it had been Yuzuki who masturbated in her room while calling my name. After overhearing that, how was I supposed to treat her like an ordinary little sister?
When that thought occurred to me, another realization flashed through my mind.
“...Was that because of the coupling too?”
Once I saw it, every lingering question seemed to dissolve.
Let’s be honest. The first time I paired with Yuzuki, only one thought had filled my head.
Not little sister, but the fact that she was an impossibly attractive woman.
The unreality of coupling with a beautiful girl I could never touch in real life had been so overwhelming…
That might have been where everything began.
The more unknown truths I uncovered, the more my thoughts twisted into chaos.
How was I supposed to face Yuzuki tomorrow…
One thing was certain: because of her, there was no way I could simply go back to sleep now.